ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
361 
as also in the main with those of Pringsheim, Meyer, Schimper, Schmitz, 
and F. Schwarz. 
When the seeds are ripe the chlorophyll-grains do not become ab- 
sorbed in the protoplasm, but only shrivel and dry up, and are then so 
concealed by the reserve-substances that they are difficult to detect. 
On germination the chlorophyll-grains again swell up, and multiply by 
a usually irregular division into four, so that the cells are filled with 
small particles which were formerly considered as microsomes of the 
protoplasm. In etiolated cotyledons the chromatophores develope in 
the same way as in green ones, but are somewhat smaller. Those coty- 
ledons which are above the surface of the soil are not only receptacles 
for reserve-substances, but also organs for assimilation, since their 
chlorophyll-grains form starch. But they do not develope in the dark 
or in diffused daylight, but only in direct sunlight. 
Experiments with Schwarz’s reagents show that the stroma of the 
chlorophyll-grains does not consist of fibrillae composed of granules and 
a matrix in which they are imbedded, but of a framework of bands, which 
holds the pigment in its meshes ; these bands are in communication one 
with another. In by far the greater number of cases no protoplasmic 
membrane could be detected surrounding the chlorophyll-grains. In 
different plants, and even in the same species, the resistant power of the 
chromatophores varies greatly ; some are completely destroyed even by 
water, while others resist much more powerful reagents. 
Origin and Development of Starch-grains.* — Herr 0. Eberdt cri- 
ticizes the conclusions arrived at by previous observers on this subject, 
and especially those of Schimper.f His observations were made on the 
epiderm of the stem and leaf-stalk of Philodendron grandifolium , rhizome 
and tubers of Canna , Stanhopea , Epipactis palustris, Convallaria majcilis, 
Phajus grandifolius , and the potato, and on the starch-grains in the lati- 
ciferous tubes of the Euphorbiaceae. 
The author agrees with Schimper in tracing the origin of the starch- 
grains in parts of plants which do not assimilate to proteinaceous bodies, 
which Schimper terms starch-generators, but which Eberdt prefers to call 
the ground-substance of starch. He dissents, however, from Schimper’s 
view that these bodies play an active part in the formation of starch ; 
and he regards them as purely passive bodies, while the active sub- 
stance is the protoplasm solely. Again, while Schimper asserts that these 
plastids (leucoplastids, chloroplastids, or chromoplastids) are present in 
the cell from the first, Eberdt maintains that they are formed out of the 
protoplasm by differentiation. 
These bodies have a tendency to move towards the cell-nucleus, and 
then either collect into groups or are scattered around it. In either 
case they are inclosed in a pellicle of protoplasm, which is connected 
by threads with the parietal protoplasm of the cell. When collected 
into groups, each one of these bodies becomes gradually transformed into 
starch from within outwards, and the protoplasm-pellicle then becomes 
detached, and finally incloses each separate group, or it is ruptured and 
the groups fall apart. In the former case the groups remain permanently 
* Jahrb. f. Wiss. Bot. (Pringsheim;, xxii. (1890) pp. 293-348 (2 pis.). 
f Cf. this Journal, 1888, p. 71. 
